JPH0674621A - Air conditioner - Google Patents

Abstract

PURPOSE:To perform sure sensing of shortage amount of refrigerant in a freezing cycle and terminate an operation of the freezing cycle by a method wherein a liquid side refrigerant pressure in the freezing cycle is detected by a pressure sensor and the lack of amount of refrigerant in the freezing cycle is detected in reference to the sensed pressure. CONSTITUTION:A liquid side refrigerant pressure in a freezing cycle is detected by a pressure sensor 13 during operation. A detected pressure of the pressure sensor 13 is compared with a predetermined set value. In this comparing operation, if the detected pressure is lower than the set value, the shortage amount of refrigerant is detected. During a cooling operation, the cooling cycle is kept as it is, and in the case that a heating operation is carried out, a cooling cycle is forcedly formed and a two-way valve 8 is closed. Refrigerant present at a distributing unit B and outdoor units C1 to C3 is drawn into an outdoor unit A and along with this operation, a pressure at a high pressure side is gradually increased. This pressure at the high pressure side is detected by a pressure sensor 12. As the detected pressure becomes more than the set value, the two- way valve 10 is closed and after this operation, the entire operation in the system is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-type air conditioner in which a plurality of indoor units are connected to an outdoor unit.

[0002]

2. Description of the Related Art A refrigerant is enclosed in a refrigeration cycle of an air conditioner, but if a refrigerant leaks and the amount of the refrigerant decreases, proper operation cannot be performed. In this case, protective means such as a high-pressure switch and a low-voltage switch attached to the refrigeration cycle will eventually operate and the operation will be stopped.

Further, suppose that, during a trial run after installation, the protective means is activated due to some abnormality and the operation is stopped. In this case, if it is suspected that the cause of the stop is an insufficient amount of refrigerant, an operation of recharging a regular amount of refrigerant during the refrigeration cycle, so-called regas operation is required.

[0004]

It takes a certain amount of time for the protection means to operate, and during that time a large load is applied to the refrigeration cycle equipment such as the compressor. Therefore, the life of the refrigeration cycle device is adversely affected.

Moreover, the regas work causes a delay in the installation work and an increase in cost, and when the replacement work is performed even if the refrigerant amount is not insufficient, time and cost are considerably wasted. In particular, in a multi-type air conditioner in which a plurality of indoor units are connected to an outdoor unit, since the refrigerant pipe is long, the amount of refrigerant enclosed is large and the regas work becomes quite difficult.

Further, if the cause of the shortage of the refrigerant amount is the leakage of the refrigerant from the indoor side pipe, a large amount of the refrigerant gas will be filled in the room as it is. In particular, in a multi-type air conditioner, a large amount of refrigerant corresponding to the number of indoor units exists on the indoor side, so leakage of the refrigerant becomes a serious problem.
This invention takes the above circumstances into consideration,

The air conditioner of claim 1 can surely detect the shortage of the refrigerant amount in the refrigeration cycle and stop the operation,
By doing so, it is possible to eliminate the adverse effect on the life of the refrigeration cycle equipment, and to prevent wasteful regas work due to a cause different from the insufficient amount of refrigerant, thereby improving the efficiency of installation work and reducing costs. .

The air conditioner according to claim 2 is a highly safe air conditioner capable of preventing further refrigerant leakage when a refrigerant shortage occurs due to refrigerant leakage from the indoor piping. To provide.

[0009]

An air conditioner according to claim 1 is an outdoor unit having a compressor and an outdoor heat exchanger, a plurality of indoor units each having an indoor heat exchanger, a compressor and an outdoor heat exchanger. A refrigeration cycle in which a refrigerant is circulated by connecting an exchanger and each indoor heat exchanger, a pressure sensor that detects the liquid-side refrigerant pressure of this refrigeration cycle, and a refrigerant pressure shortage in the refrigeration cycle is detected from the pressure detected by this pressure sensor. And means for stopping the operation and notifying that when the shortage of the refrigerant amount is detected.

An air conditioner according to a second aspect of the invention includes an outdoor unit having a compressor and an outdoor heat exchanger, a plurality of indoor units each having an indoor heat exchanger, a compressor, an outdoor heat exchanger, and indoor heat exchangers. A refrigeration cycle in which a refrigerant is circulated by connecting an exchanger, a pressure sensor for detecting the liquid-side refrigerant pressure of this refrigeration cycle, a means for detecting a refrigerant shortage in the refrigeration cycle from the pressure detected by this pressure sensor, and this refrigerant. A means for recovering the refrigerant on the indoor unit side to the outdoor unit side when the shortage of the amount is detected and thereafter stopping the operation is provided.

[0011]

In the air conditioner of the first aspect, the pressure of the liquid side refrigerant in the refrigeration cycle is detected by the pressure sensor, and the insufficient amount of refrigerant in the refrigeration cycle is detected from the detected pressure. When this shortage of the refrigerant amount is detected, the operation is stopped and the fact is notified.

In the air conditioner of the second aspect, the pressure of the liquid side refrigerant in the refrigeration cycle is detected by the pressure sensor, and the insufficient amount of refrigerant in the refrigeration cycle is detected from the detected pressure. When this shortage of the refrigerant amount is detected, the refrigerant on the indoor unit side is collected on the outdoor unit side, and then the operation is stopped.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, A is an outdoor unit,
Plural indoor units C ₁ , C ₂ and C ₃ are connected to the outdoor unit A through a distribution unit B by piping. The outdoor unit A includes compressors 1 and 2. The compressor 1 is an inverter driven variable capacity compressor, and the compressor 2 is a commercial power source driven fixed capacity compressor.

An outdoor heat exchanger 5 is connected to the discharge ports of the compressors 1 and 2 through a check valve 3 in the forward direction and a four-way valve 4, respectively. A header H is connected to the outdoor heat exchanger 5 via a check valve 6 for forming a cooling cycle, a liquid receiver (liquid tank) 7, and a two-way valve 8. An expansion valve (pressure reducer) 9 for heating is connected in parallel with the check valve 6.

The header H is provided with flow rate adjusting valves 21, 31, 41.
The indoor heat exchangers 24, 34, 44 are connected via a parallel circuit of the expansion valves (pressure reducers) 22, 32, 42 for cooling and the check valves 23, 33, 43 for forming a heating cycle.
The header H is connected to the indoor heat exchangers 24, 34 and 44, and the header H is connected to the suction ports of the compressors 1 and 2 via the two-way valve 10, the four-way valve 4 and the accumulator 11. .

Thus, the outdoor unit A, the distribution unit B, and the indoor units C ₁ , C ₂ , and C ₃ constitute a heat pump type refrigeration cycle, and during the cooling operation, the refrigerant is caused to flow in the direction of the solid line arrow in the drawing to cool the room. A cycle is formed, and the outdoor heat exchanger 5 is connected to the condenser and the indoor heat exchangers 24, 3
4,44 function as an evaporator. During the heating operation, by switching the four-way valve 4, the refrigerant is caused to flow in the direction of the broken line arrow to form a heating cycle, and the indoor heat exchangers 24, 34, 44 are formed.
To function as a condenser and the outdoor heat exchanger 5 as an evaporator.

The flow rate adjusting valves 21, 31, 41 are pulse motor valves whose opening continuously changes according to the number of drive pulses supplied. Hereinafter, the flow rate adjusting valve is abbreviated as PMV.

The expansion valves 22, 32, 42 have temperature sensitive tubes 22a, 32a, 42a, respectively. The difference between the temperature sensed by these temperature sensitive tubes and the temperature of the refrigerant flowing through the valve body (indoor heat exchange). The degree of opening automatically changes according to the degree of refrigerant superheat in the vessel. The temperature sensing tube 2 of the expansion valves 22, 32, 42
2a, 32a, 42a to the indoor heat exchangers 24, 34, 44
And the header H on the gas side pipe.

On the indoor unit A side of this refrigeration cycle, a pressure sensor 12 is attached to the high pressure side pipe between the check valves 3 and 3 and the four-way valve 4. A pressure sensor 13 is attached to the liquid side pipe between the liquid receiver 7 and the two-way valve 8. The control circuit is shown in FIG.

The outdoor unit A has an outdoor controller 50. The distribution control unit 60 of the distribution unit B is connected to the outdoor control unit 50, and the indoor control units 70 of the indoor units C ₁ , C ₂ , C ₃ are connected to the distribution control unit 60.

The outdoor control unit 50 comprises a microcomputer and its peripheral circuits. In this outdoor control unit 50,
The four-way valve 4, the two-way valves 8 and 10, the pressure sensors 12 and 13, the inverter 51, the switch 52, and the notification means such as the display 54 are connected.

The inverter 51 rectifies the voltage of the AC power supply 53, converts it into a voltage of a predetermined frequency by switching according to a command from the outdoor control unit 50, and outputs it. This output becomes the drive power for the compressor motor 1M. The switch 52 is, for example, a relay contact. This switch 52
The compressor motor 2M is connected to the AC power supply 53 via the. The distribution control unit 60 is composed of a microcomputer and its peripheral circuits. PMV2 is added to the distribution control unit 60.
1, 31, 41 are connected.

The indoor controller 70 comprises a microcomputer and its peripheral circuits. In this indoor control unit 70,
A remote control type operation device (hereinafter, abbreviated as a remote control) 71 and an indoor temperature sensor 72 are connected.
The indoor control unit 70 includes the following functional means. [1] Distributing the operation start command, operation mode setting command, and operation stop command based on the operation of the remote controller 71 to the distribution unit B
Means to send to.

[2] A means for obtaining the difference between the temperature detected by the room temperature sensor 72 and the room temperature set by the remote controller 71 as an air conditioning load, and sending the data to the distribution unit B with the air conditioning load as the required capacity. The distribution control unit 60 includes the following functional means. [1] Means for obtaining the total required capacity of the indoor units C ₁ , C ₂ , C ₃ and sending the data of the total required capacity to the outdoor unit A. [2] Means for controlling the opening degree of the PMVs 21, 31, 41 according to the required capacity of the indoor units C ₁ , C ₂ , C ₃ . The outdoor control unit 50 includes the following functional means. [1] A means for controlling the operation of the compressors 1 and 2 and the operating frequency F of the compressor 1 in accordance with the sum of required capacities. [2] A means for detecting the shortage of the refrigerant amount in the refrigeration cycle from the liquid-side refrigerant pressure Pr detected by the pressure sensor 13.

[3] When a shortage of the amount of refrigerant is detected, the refrigerant on the indoor units C ₁ , C ₂ , C ₃ side is collected on the outdoor unit A side, after which the operation is stopped, and the error indicator 54
Means to notify in. Next, the operation of the above configuration will be described with reference to FIGS.

In the cooling operation, the refrigerant discharged from the compressors 1 and 2 is caused to flow in the direction of the solid line arrow in FIG. 1 to form a cooling cycle, and the outdoor heat exchanger 5 is set to the condenser and the indoor heat exchangers 24 and 3.
4,44 function as an evaporator.

In the heating operation, by switching the four-way valve 4, the refrigerant discharged from the compressors 1 and 2 is caused to flow in the direction of the broken line arrow to form a heating cycle, and the indoor heat exchangers 24, 34,
44 functions as a condenser, and the outdoor heat exchanger 5 functions as an evaporator. During operation, the operation frequency of the compressors 1 and 2 and the operation frequency F of the compressor 1 are switched to a plurality of patterns in accordance with the total required capacity of the indoor units C ₁ , C ₂ , and C ₃ .

That is, when the required capacity is small, a single capacity variable operation of the compressor 1 is executed. When the required capacity is slightly increased, the capacity variable operation of the compressor 1 and the capacity fixed operation of the compressor 2 are executed.

During operation, the refrigerant pressure Pr on the liquid side of the refrigeration cycle
Is detected by the pressure sensor 13. This liquid side refrigerant pressure Pr
As shown in FIG. 3, is characterized in that the enclosed refrigerant amount in the refrigeration cycle is high if it is in the vicinity of the normal amount, and it greatly decreases as the refrigerant amount decreases. In addition, the change ΔPr in the liquid-side refrigerant pressure due to this decrease in the refrigerant amount is much larger than the change ΔPd in the high-pressure side pressure.

The detected pressure Pr of the pressure sensor 13 is compared with a preset set value P ₁ . Here, when the detected pressure Pr becomes lower than the set value P ₁ (Pr <P ₁ ),
An insufficient amount of refrigerant is detected. If insufficient refrigerant is detected,
In the cooling operation, the cooling cycle is formed as it is, and in the heating operation, the cooling cycle is forcibly formed. And first, the two-way valve 8
Is closed.

When the two-way valve 8 is closed, the flow of the refrigerant from the outdoor unit A toward the distribution unit B and the indoor units C ₁ , C ₂ , C ₃ is shut off, and the distribution unit B and the indoor units C ₁ , C ₂ , The refrigerant already existing on the C ₃ side is sucked into the outdoor unit A side.

As the recovery of the refrigerant to the outdoor unit A progresses in this way, the high pressure side pressure Pd gradually rises accordingly. This high-pressure side pressure Pd is detected by the pressure sensor 12, and when the detected pressure Pd becomes equal to or higher than the set value, the two-way valve 10 is closed under the judgment that the refrigerant recovery is completed. The set value for the detected pressure Pd is lower than the operating point of the high pressure protection means.

When the two-way valve 10 is closed, the recovered refrigerant is trapped in the outdoor unit A side. After that, all the operations are stopped, and the fact that the refrigerant amount is insufficient is displayed on the display 54 in characters.

As described above, when the amount of the refrigerant is insufficient, the refrigerant on the distribution unit B side and the indoor units C ₁ , C ₂ , C ₃ side is simply recovered to the outdoor unit A side, and the operation is stopped immediately thereafter. The adverse effect on the life of the refrigeration cycle equipment can be eliminated.

In addition, since the cause of the operation stop is that the amount of the refrigerant is insufficient, a character is displayed on the display 54. Therefore, for example, at the time of a trial operation after installation, the worker can re-insert the regular amount of the refrigerant only when the amount of the refrigerant is insufficient. It suffices to carry out gas work, and unnecessary re-gas work due to a cause other than insufficient refrigerant is prevented. Therefore, the efficiency of installation work and cost reduction can be achieved.

Further, when the cause of the shortage of the amount of refrigerant is the leakage of the refrigerant from the indoor side pipe, all the refrigerant remaining on the indoor side is recovered by the outdoor unit A, so that further leakage of the refrigerant is prevented. . Therefore, it is possible to prevent the refrigerant gas from being filled in the room as much as possible, and improve the safety.

In the above embodiment, the completion of the refrigerant recovery is detected from the pressure (high pressure side pressure) Pd detected by the pressure sensor 12. However, the pressure sensors are attached to the suction side pipes of the compressors 1 and 2. The recovery completion may be detected based on the low pressure side pressure Ps detected at. This focuses on the fact that the low-pressure side pressure Ps decreases as the refrigerant recovery progresses. In the above embodiment, the case where the number of compressors is two has been described as an example, but the number of compressors can be set appropriately.

[0038]

As described above, according to the present invention,

In the air conditioner of the first aspect, the pressure of the liquid side refrigerant in the refrigerating cycle is detected by the pressure sensor, the insufficient amount of refrigerant in the refrigerating cycle is detected from the detected pressure, and the operation is stopped when the insufficient amount of refrigerant is detected. In addition, since it is configured to notify that effect, it is possible to reliably detect the shortage of the refrigerant amount of the refrigeration cycle and stop the operation, thereby eliminating the adverse effect on the life of the refrigeration cycle equipment, and the refrigerant. It is possible to prevent wasteful regas work due to a cause different from the insufficient amount and improve the efficiency of installation work and reduce costs.

According to another aspect of the air conditioner of the present invention, the pressure of the refrigerant on the liquid side of the refrigeration cycle is detected by the pressure sensor, the insufficient amount of refrigerant in the refrigeration cycle is detected from the detected pressure, and when the insufficient amount of refrigerant is detected, the indoor unit side is detected. Since the refrigerant is collected to the outdoor unit side and the operation is stopped after that, if a refrigerant shortage occurs due to the leakage of the refrigerant from the indoor side pipe,
Further leakage of the refrigerant can be prevented and safety can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a refrigeration cycle according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a control circuit of the same embodiment.

FIG. 3 is a graph showing the relationship between the amount of enclosed refrigerant and the pressure of each part in the refrigeration cycle of the example.

FIG. 4 is a flowchart for explaining the operation of the embodiment.

[Explanation of symbols]

A ... Outdoor unit, B ... Distribution unit, C ₁ , C ₂ , C
₃ ... Indoor unit, 1 ... Variable capacity compressor, 2 ... Fixed capacity compressor, 13 ... Pressure sensor, 50 ... Outdoor control section, 54 ...
Display (informing means), 60 ... Distribution control unit, 70 ... Indoor control unit.

Claims (2)

[Claims] 1. An outdoor unit having a compressor and an outdoor heat exchanger, a plurality of indoor units each having an indoor heat exchanger, the compressor, the outdoor heat exchanger, and each indoor heat exchanger connected to each other. A refrigeration cycle that circulates a refrigerant, and a pressure sensor that detects the liquid-side refrigerant pressure of this refrigeration cycle,
An air conditioner comprising means for detecting a refrigerant amount shortage of the refrigeration cycle from the pressure detected by the pressure sensor, and means for notifying the operation and notifying the fact when the refrigerant amount shortage is detected. . 2. An outdoor unit having a compressor and an outdoor heat exchanger, a plurality of indoor units each having an indoor heat exchanger, the compressor, the outdoor heat exchanger, and each indoor heat exchanger connected to each other. A refrigeration cycle that circulates a refrigerant, and a pressure sensor that detects the liquid-side refrigerant pressure of this refrigeration cycle,
Means for detecting a refrigerant amount shortage of the refrigeration cycle from the pressure detected by the pressure sensor, and means for collecting the refrigerant on the indoor unit side to the outdoor unit side when detecting the refrigerant amount shortage and thereafter stopping the operation An air conditioner characterized by that.